The present invention relates to an apparatus, system and method for the production of high-quality materials. More specifically, the present invention relates to the thermal inspection of materials, location and/or geometry of defects in those materials, and providing of feedback into a processing control to identify, reduce, and remove the incidences of defect production in the material.
Thermography is generally known. It is used, e.g., in probing aircraft surfaces and other materials for hidden cracks and flaws.
U.S. Pat. No. 5,711,603 discloses a transient depth thermography technique for the nondestructive testing of objects. The method includes steps of heating the surface of an object, recording pixel intensity for each pixel in a heated surface, and determining pixel contrast from pixel intensity. The method monitors the pixel contrast over successive images to determine the location of a flaw within an object and the surface can be depicted on a print which correlates the flaws with their depth coded by color.
U.S. Pat. No. 5,705,821 discloses a method and apparatus for checking IC chips for defects by scanning fluorescent microthermal imaging. The method uses a scanned and focused laser beam to excite a thin fluorescent film disposed on the surface of an integrated circuit chip. Localized heating associated with IC chip defects is observed by collecting fluorescent radiation from the film and forming a thermal map.
U.S. Pat. No. 5,582,485 discloses a method of analyzing structures by time-varying thermal signals. A projector projects a moving pattern of heat onto a test object, and an infrared camera insensitive to the projected wavelength detects emitted heat from the object. Variances in the pattern are caused by heat buildup by resistance to downward and lateral flows of heat energy, and thus may detect cracks and debonding simultaneously.
U.S. Pat. No. 5,444,241 discloses a dual-band infrared imaging method. Computerized tomography images the structure using infrared radiation. A structure to be imaged is heated by at least two different wavelengths of infrared radiation, images are sequentially obtained, and the images are utilized to determine whether a flaw is present.
U.S. Pat. No. 5,032,727 discloses the detection of defects in manufactured products by thermal ratio analysis, which is said to involve the ratios of thermal data and their analysis including statistical analysis. Also disclosed is image enhancement and the rejection of known artifacts.
The present invention provides an apparatus and method for improving product quality of products produced by batch or continuous processes wherein one or more process variables are controlled as a function of at least one product characteristic monitored during manufacture thereof. Alternatively, the apparatus and method can be used to identify the location and/or geometry of flaws in material produced by a continuous or batch process.
According to one embodiment of the invention, the apparatus can include a central process controller, a thermal gradient initiator, an infrared detector and a computer. The controller can include hardware and/or software effective to control one or more process variables during manufacture of a product in a manufacturing line, the thermal gradient initiator can provide a thermal gradient within the product at a location along the manufacturing line, and the infrared detector can be positioned to receive a thermographic image of the product at or downstream of the thermal gradient initiator. The computer preferably includes hardware and/or software to communicate with the central process controller, receive and analyze the image from the infrared detector, and determine at least one physical characteristic of the product, and output data corresponding to the determined physical characteristic to the central process controller. The central process controller can also modify one or more of the process variables when the determined physical characteristic is outside a range of predetermined values for the physical characteristic.
According to another embodiment of the invention, the apparatus can be used for inspecting a sheet material produced by a production process having a process flow wherein the apparatus includes a central process controller, a source of incident radiation, a conveyor, an infrared detector, and a computer. The central process controller can be configured to control at least one aspect of the production process, the source of incident radiation can be arranged to impinge upon the sheet material, the conveyor can be arranged to move the sheet material in a single plane, and the infrared detector can be located proximate to a surface of the sheet material so as to create an image of the surface of the sheet material at or downstream of the source of incident radiation. The computer can be in communication with the central process controller and configured to receive and analyze the image from the infrared detector to determine physical characteristics of the sheet material, and transmit the determined physical characteristics to the central process controller, so that the central process controller adjusts the at least one aspect of the production process in response to the determined physical characteristic.